I got a client for fixing website issues of mobile browsers. I did everything else but stuck with FireFox pop up. Here on this [https://www.robuxgeneratorz.com/ website] on the sidebar, when you submit the newsletter, on every other browser including IE, it brings up a pop up with success message. But on Firefox, the JS code doesn't seem to work, can anyone help me identify if the problem is in theme's code of is it some issue with mobile browser. I am using latest updated version of Firefox.